The Ministry of Health cleared the Rio de la Plata for port operations despite knowing it was connected to an Australian Covid-19 case, Maritime NZ says.
Now 11 of the 21 crew on board the ship, anchored near Mōtītī Island, have tested positive for Covid-19 resulting in 98 Port of Tauranga workers self-isolating.
Family members of the port workers have not been asked to self-isolate, a port spokeswoman said.
Yesterday afternoon, Covid-19 Minister Chris Hipkins said only about nine of the 98 workers were fully vaccinated and two had received their first dose.
"Those numbers are too low."
Prime Minister Jacinda Ardern said "hesitancy and mis-information" had slowed down the vaccination rollout at the port of Tauranga.
She pointed out that it was now mandatory for those workers to be vaccinated by the end of September "or it may mean job loss".
Hipkins said yesterday afternoon 23 negative results had come back so far, including from the Port of Tauranga pilot who had taken the ship out. This morning he told Newstalk ZB that 65 of the workers had tested negative. Results from the remainder of the workers are not yet back.
Health authorities were looking at whether it was known there were sick people on board when the ship was unloaded.
He said it was not always possible to test a ship's crew before unloading.
"But we will look at who knew what, when," and what decisions were made.
The Rio de la Plata crew were tested as part of the requirements for entry to Napier, its next destination.
Port operations were initially shut down last week when cargo left the vessel, despite the Ministry of Health giving the all-clear for operations, Maritime NZ has confirmed.
A spokesman said it received an email from its Australian counterparts at 2.36pm on Tuesday after a maritime pilot who boarded the vessel in Australia tested positive for Covid-19.
The pilot developed symptoms and tested positive for the Delta variant nine days after being on board and was not linked to other cases.
Marine pilots help in manoeuvring ships while arriving or departing a port.
"Maritime NZ passed this information to the Ministry of Health and to the port.
"The Ministry of Health subsequently advised that the vessel was safe to commence port operations.
"Maritime NZ passed this information to the port," the spokesman said.
The Bay of Plenty Times reported last week a Port of Tauranga pilot boarded the vessel at 5pm on Wednesday and brought the ship to the Tauranga Container Terminal. Customs NZ then shut down the port, a Port of Tauranga spokeswoman said at the time.
"About 9pm, Customs NZ unexpectedly shut down operations on the ship and the local Public Health Unit advised Port of Tauranga that our pilot and the stevedores unloading the ship should go home and isolate while awaiting further instructions."
Asked why Customs "unexpectedly" shut down operations despite the Ministry of Health clearing the vessel for operations, Customs' maritime group manager Robert Smith said it was standard protocol.
"Based on information received by Customs, standard maritime border protocols were observed.
"Customs was notified at approximately 8pm by our international partners."
Toi Te Ora advised the port on Thursday port operations could resume on the vessel and workers no longer needed to isolate.
Hipkins said it was not yet known why the unloading of the ship was paused, and then restarted.
The Rio de la Plata left the port on Saturday and has been anchored near Mōtītī Island awaiting results of swabs taken from the crew.
At yesterday's 1pm news briefing, the Ministry of Health said 91 port workers had been tested by 11.30am and the first results were expected that evening.
"Some workers will require a second test, based on their contact with the ship, and will be required to remain in isolation until the result of those second tests are known," it said.
All those isolating had contact with the ship or unloaded cargo in shifts over the four days the ship was berthed at the Port of Tauranga.
Port workers had been asked to self-isolate, "out of an abundance of caution", a Port of Tauranga spokeswoman said.
The families of those workers had not been asked to isolate, she confirmed.
"Cargo loading and unloading at Tauranga Container Terminal will operate at reduced levels whilst we work through this situation.
"Port of Tauranga treats all vessels as if they have Covid-19 on board and all port workers who interacted with the ship followed the usual Covid-19 precautions, including physical distancing and wearing PPE."
Toi Te Ora referred all questions to the Ministry of Health, including why the ship was "cleared" to berth at the Port of Tauranga.
The Ministry of Health has been approached for comment.
Bay of Plenty District Health Board Covid-19 incident controller Trevor Richardson said there was sufficient testing across the Bay of Plenty, with most available through general practices.
The urgent care clinic in Tauranga is based at Accident and Health Care on 2nd Avenue, which is open Monday to Sunday, 8 am to 6 pm.
The health board was standing by to provide additional community-based testing if required, he said.
Rail and Maritime Transport Union president Aubrey Wilkinson declined to speak on the incident because the information from health officials had not been made clear to them yet.
What concern is there for the community?
Otago University epidemiologist Michael Baker said the risk to the wider community came down to how much contact port workers had with crew, what PPE procedures were in place and vaccination rates.
"We just don't know the level of risk because there is not enough information.
"The fact they are all being tested will give us some insight."
He said the community needed to remain vigilant and stay at home if flu or cold symptoms developed.
"That's always standard advice but it is particularly important now since there is a heightened level of risk."
Baker didn't rule out health authorities raising the alert level, if necessary.
Dr Andrew Chen, a researcher at University of Auckland-based Koi Tū: The Centre for Informed Futures, was concerned about the level of use of the Covid Tracer App.
He believed if people had just begun to scan, it was probably too late.
"If they start doing it once a case is in the community, it's probably already too late. It is about both protecting yourself and the community around you."
Chen said these cases were a reminder to be more careful and vigilant than we otherwise would be.